System for discharging heat out of head-mounted display based on hybrid fan and heat pipe

ABSTRACT

A head-mounted display (HMD) includes a hybrid fan, a printed circuit board (PCB) with one or more electronic components and a heat pipe to dissipate heat. The hybrid fan has a center axis extending from a rear side of the HMD to a front side of the HMD. The hybrid fan pulls air from a rear side of the HMD. The heat pipe has an end coupled to the PCB. The heat pipe partially surrounds a periphery of the hybrid fan and transfers heat away from at least the PCB. The HMD further includes a side cover and a front cover. The side cover encloses the hybrid fan, the PCB and the heat pipe. The front cover is attached to the side cover with a slit between an outer edge of the front cover and an outer edge of the side cover to discharge air from the hybrid fan.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. application Ser.No. 15/491,522, filed Apr. 19, 2017, which is incorporated by referencein its entirety.

BACKGROUND

The present disclosure generally relates to a system for dissipatingheat generated in a head-mounted display (HMD), and specifically relatesto a system for discharging heat out of the HMD based on a hybrid fanand a heat pipe.

The HMD can operate as part of, e.g., a virtual reality (VR) system, anaugmented reality (AR) system, a mixed reality (MR) system, or somecombination thereof. During operations of the HMD, heat is generatedinside the HMD. The heat in the HMD may be generated by one or moreelectronic components of the HMD, by a face of a user wearing the HMD,etc. For proper operations of the HMD, the heat generated inside the HMDneeds to be efficiently discharged out of the HMD.

SUMMARY

Embodiments of the present disclosure relate to a head-mounted display(HMD) that comprises a hybrid fan, a printed circuit board (PCB) withone or more electronic components and a heat pipe. The hybrid fan has acenter axis extending from a rear side of the HMD to a front side of theHMD. The hybrid fan is configured to pull air from a rear side of theHMD. The heat pipe has an end coupled to the PCB. The heat pipe at leastpartially surrounds a periphery of the hybrid fan and transfers heataway from at least the PCB. The HMD further includes a side cover and afront cover. The side cover encloses the hybrid fan, the PCB and theheat pipe. The front cover is attached to the side cover with a slitbetween an outer edge of the front cover and an outer edge of the sidecover to discharge air from the hybrid fan.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a head-mounted display (HMD), inaccordance with an embodiment.

FIG. 2A is a perspective view of a front rigid body of the HMD in FIG. 1without a front cover and showing components within the front rigidbody, in accordance with an embodiment.

FIG. 2B is a perspective view of the front rigid body of the HMD in FIG.1 without a front cover and showing a heat pipe coupled to a printedcircuit board (PCB), in accordance with an embodiment.

FIG. 3 is a cross-sectional view of the front rigid body of the HMD inFIG. 1 taken along line A-A′ of FIG. 2B, in accordance with anembodiment.

FIG. 4 is a rear view of the front rigid body of the HMD in FIG. 1,showing a view of a hybrid fan from a facial interface of the HMD, inaccordance with an embodiment.

The figures depict embodiments of the present disclosure for purposes ofillustration only. One skilled in the art will readily recognize fromthe following description that alternative embodiments of the structuresand methods illustrated herein may be employed without departing fromthe principles, or benefits touted, of the disclosure described herein.

DETAILED DESCRIPTION

Embodiments of the present disclosure relate to a head-mounted display(HMD) with thermal exhaust design that includes a hybrid fan and a heatpipe. The hybrid fan discharges heat through a front side of the HMD. Aprinted circuit board (PCB) including a central processing unit (CPU)may be placed below a top surface of the HMD and connected to the heatpipe to transfer heat away from the CPU effectively. The HMD alsoincludes a metal frame that acts as a heat sink in addition to providingstructural support.

FIG. 1 is a perspective view of HMD 100, in accordance with anembodiment. The HMD 100 may be part of a virtual reality (VR) system.The HMD 100 may include, among other components, a front rigid body 105,a head band 110, a front cover 115, and a side cover 120. The side cover120 encloses components for discharging heat generated inside the HMD100, as discussed in detail in conjunction with FIGS. 2A-2B, FIG. 3 andFIG. 4. The front cover 115 is attached to the side cover 120 with aslit 125 between an outer edge of the front cover 115 and an outer edgeof the side cover 120 to discharge air and heat out of the HMD 100.

The HMD 100 shown in FIG. 1 also includes camera assemblies 130 locatedon top and bottom portions of the front cover 115. In some embodiments,each camera assembly 130 can be implemented as a depth camera assembly(DCA) that determines depth information of a local area surrounding someor all of the HMD 100. Each camera assembly 130 includes an imagingaperture and an illumination aperture (not shown in FIG. 1), and anillumination source (not shown in FIG. 1) of the camera assembly 130emits light through the illumination aperture. The illumination sourceof the camera assembly 130 may be composed of a plurality of laser-typelight emitters on a single substrate that simultaneously or in differenttime instants emit a plurality of light beams, e.g., in the form of astructured light pattern. An imaging device (not shown in FIG. 1) of thecamera assembly 130 captures light from the illumination source that isreflected and/or scattered from the local area through the imagingaperture. A controller (not shown in FIG. 1) coupled to the imagingdevice or integrated within the imaging device of the camera assembly130 may determine two-dimensional or three-dimensional information ofone or more objects in the local area based on the capturedreflected/scattered light. The same or a separate controller can controloperation of the illumination source of the camera assembly 130.

The HMD 100 shown in FIG. 1 also includes a wireless transceiver 135. Insome embodiments, the HMD 100 wirelessly communicates with a console(not shown in FIG. 1) via the wireless transceiver 135. The console mayprovide content to the HMD 100 for processing in accordance withinformation received from the HMD 100. The HMD 100 may transmit theinformation to the console via the wireless transceiver 135. The HMD mayfurther receive the content from the console via the wirelesstransceiver 135. In some embodiments, the console generates atwo-dimensional and/or three-dimensional mapping of the local areasurrounding some or all of the HMD 100 based on information receivedfrom the HMD 100. In some embodiments, the console determines depthinformation for the three-dimensional mapping of the local area based oninformation received from the camera assembly 130 that is relevant fortechniques used in computing depth. The HMD 100 may provide to theconsole, e.g., via the wireless transceiver 135, position information,acceleration information, velocity information, predicted futurepositions, or some combination thereof, of the HMD 100. Based on thereceived information, the console determines content to provide to theHMD 100 for presentation to the user.

In one embodiment, the front rigid body 105 includes one or moreelectronic display elements (not shown in FIG. 1), one or moreintegrated eye tracking systems (e.g., one eye tracking system for eacheye of a user wearing the HMD 100, not shown in FIG. 1) that estimate aposition and angular orientation of the user's eyes, an InertialMeasurement Unit (IMU) (not shown in FIG. 1), one or more positionsensors (not shown in FIG. 1), and a reference point (not shown in FIG.1). The position sensors may be located within the IMU, and neither theIMU nor the position sensors are visible to a user of the HMD 100. TheIMU is an electronic device that generates fast calibration data basedon measurement signals received from one or more of the positionsensors. A position sensor generates one or more measurement signals inresponse to motion of the HMD 100. Examples of position sensors include:one or more accelerometers, one or more gyroscopes, one or moremagnetometers, another suitable type of sensor that detects motion, atype of sensor used for error correction of the IMU, or some combinationthereof. The position sensors may be located external to the IMU,internal to the IMU, or some combination thereof.

The one or more electronic display elements of the HMD 100 may beintegrated into an electronic display (not shown in FIG. 1). Theelectronic display generates image light. In some embodiments, theelectronic display includes an optical element that adjusts the focus ofthe generated image light. The electronic display displays images to theuser in accordance with data received from a console (not shown in FIG.1). In various embodiments, the electronic display may comprise a singleelectronic display or multiple electronic displays (e.g., a display foreach eye of a user). Examples of the electronic display include: aliquid crystal display (LCD), an organic light emitting diode (OLED)display, an inorganic light emitting diode (ILED) display, anactive-matrix organic light-emitting diode (AMOLED) display, atransparent organic light emitting diode (TOLED) display, some otherdisplay, a projector, or some combination thereof. The electronicdisplay may also include an aperture, a Fresnel lens, a convex lens, aconcave lens, a diffractive element, a waveguide, a filter, a polarizer,a diffuser, a fiber taper, a reflective surface, a polarizing reflectivesurface, or any other suitable optical element that affects the imagelight emitted from the electronic display.

The HMD 100 may also include an optical assembly (not shown in FIG. 1).The optical assembly magnifies received light from the electronicdisplay, corrects optical aberrations associated with the image light,and the corrected image light is presented to a user of the HMD 100. Atleast one optical element of the optical assembly may be an aperture, aFresnel lens, a refractive lens, a reflective surface, a diffractiveelement, a waveguide, a filter, a reflective surface, a polarizingreflective surface, or any other suitable optical element that affectsthe image light emitted from the electronic display. Moreover, theoptical assembly may include combinations of different optical elements.In some embodiments, one or more of the optical elements in the opticalassembly may have one or more coatings, such as anti-reflectivecoatings, dichroic coatings, etc. Magnification of the image light bythe optical assembly allows elements of the electronic display to bephysically smaller, weigh less, and consume less power than largerdisplays. Additionally, magnification may increase a field of view ofthe displayed media. For example, the field of view of the displayedmedia is such that the displayed media is presented using almost all(e.g., 110 degrees diagonal), and in some cases all, of the user's fieldof view. In some embodiments, the optical assembly is designed so itseffective focal length is larger than the spacing to the electronicdisplay, which magnifies the image light projected by the electronicdisplay. Additionally, in some embodiments, the amount of magnificationmay be adjusted by adding or removing optical elements.

FIG. 2A is a perspective view 200 of the front rigid body 105 of the HMD100 in FIG. 1 without the front cover 115, in accordance with anembodiment. The front cover 115 is removed in FIG. 2A so that differentcomponents placed within the front rigid body 105 can be illustrated. Asshown in FIG. 2A, the front rigid body 105 includes a hybrid fan 205, aprinted circuit board (PCB) 210 with one or more electronic components,and a heat pipe 215. The side cover 120 encloses the hybrid fan 205, thePCB 210 and the heat pipe 215. The front rigid body 105 further includesa metal frame 220 onto which the PCB 210 is mounted. The metal frame 220acts as a heat sink in addition to providing structural support, asdiscussed in more detail in conjunction with FIG. 2B. The metal frame220 is formed with a hole 225 to receive the hybrid fan 205, and themetal frame 220 is also enclosed within the side cover 120. The metalframe 220 has edges shaped with contours that match an internal contourof the side cover 120 to support the side cover 120. In an embodiment,the metal frame 220 is made of magnesium. In alternate embodiments, themetal frame 220 can be made of other metals or combination of metals.

The hybrid fan 205 has a center axis extending from a rear side of thefront rigid body 105 to a front side of the front rigid body 105. Thehybrid fan 205 pulls air from the rear side of the front rigid body 105to the front side of the front rigid body 105. For example, the hybridfan 205 pulls the air (e.g., warm and moist air) from a cavity between aface of a user wearing the HMD 100 and the front rigid body 105 to cooldown temperature in the cavity. The hybrid fan 205 exhausts the air atsides of the axial fan 205 after pulling the air from the rear side ofthe front rigid body 105. In this way, the hybrid fan 205 dischargesheat from the user's face or the facial cavity out of the HMD 100 andalso cools electronic components of the PCB 210. More details about airflows for discharging heat out of the HMD 100 are disclosed inconjunction with FIG. 3. In some embodiments, the hybrid fan 205 pullsair from front slots on the hybrid fan 205. The air pulled from thefront slots are exhausted at sides of the hybrid fan 205 for cooling theelectronic components of the PCB 210. In some embodiments, various typesof fans other than the hybrid fan 205 can be utilized for dischargingheat out of the HMD 100 and for cooling the electronic components of thePCB 210.

The PCB 210 is mounted on the metal frame 220. The PCB 210 includes oneor more electronic components that perform different operations in theHMD 100. In some embodiments, the PCB 210 includes a central processingunit (CPU) 230 that performs computation operations in the HMD 100. TheCPU 230 and other electronic components of the PCB 210 generate heatwhen performing the operations in the HMD 100. To reliable operate theHMD 100, the heat generated by the one or more electronic components ofthe PCB 210 is discharged out of the HMD 100 and a temperature of eachelectronic component is kept below a threshold level.

For efficient transferring of heat away from the PCB 210, the heat pipe215 is included in the front rigid body 105 of the HMD 100. The heatpipe 215 at least partially surrounds a periphery of the hybrid fan 205,as further shown in FIG. 2B. In one embodiment, as shown in FIGS. 2A-2B,the heat pipe 215 is designed as a horseshoe shaped object with a firstmember 235, a second member 240 extending parallel to the first member235 and a third member 245 connecting the first member 235 and thesecond member 240. In an alternate embodiment (not shown in FIGS.2A-2B), the third member is removed for weight and cost savings. In thiscase, the heat pipe 215 is composed of the first member 235 and thesecond member 240 extending parallel to the first member 235, whereinthe first member 235 and the second member 240 are not connected. Insome embodiments, one end of the heat pipe 215, e.g., an end of thefirst member 235, is coupled to the PCB 210.

The first member 235 of the heat pipe 215 is coupled to the PCB 210 viaa metal bracket 250, a metal plate 255 and a resilient material 260placed in an opening of the metal plate 255. As shown in FIG. 2B, themetal plate 255 is placed beneath the first member 235 of the heat pipe215, and the metal plate 255 is directly coupled to the PCB 210. Themetal bracket 250 is placed on top of the first member 235 of the heatpipe 215, thus securing the heat pipe 215 to the PCB 210. As shown inFIG. 2A, screws positioned in holes of the metal bracket 250 are placedon corresponding screw bosses protruding from portions of the PCB 210around the CPU 230, thus attaching the metal bracket 250 and the heatpipe 215 to the PCB 210. The metal bracket 250 and the heat pipe 215 canbe attached to the PCB 210 utilizing a mounting hardware different thanthat illustrated in FIG. 2A. In some embodiments, to facilitate transferof heat from the CPU 230 to the heat pipe 215, a thermal interfacematerial 265 is put on top of the CPU 230. Specifically, the end of thefirst member 235 of the heat pipe 215 is coupled to the CPU 230 via thethermal interface material 265. The thermal interface material 265 canbe a thermal paste or a thermal grease. In alternate embodiments (notshown in FIG. 2A), the thermal interface that couples the end of thefirst member 235 of the heat pipe 215 to the CPU 230 is implemented as aphase change pad. Other components different from the components shownin FIG. 2A can be utilized for coupling the first member 235 of the heatpipe 215 to the PCB 210.

FIG. 2B is a perspective view 270 of the front rigid body 105 of the HMD100 without the front cover 115, in accordance with an embodiment. Theview 270 of FIG. 2B shows the heat pipe 215 coupled to the PCB 210 andmounted on the metal frame 220. The heat pipe 215 is secured to the PCB210 by the metal bracket 250. As shown in FIG. 2B, one end of the firstmember 235 of the heat pipe 215 is placed between the metal bracket 250and the metal plate 255. The metal plate 255 is directly coupled to thePCB 210 and the CPU 230 (not shown in FIG. 2B) via the thermal paste 265(not shown in FIG. 2B).

The heat pipe 215 is connected to the metal frame 220 to transfer heataway from the one or more electronic components of the PCB 210 into themetal frame 220 that acts as a main heat sink. The metal frame 220spreads the heat, thus facilitating discharging the heat out of thefront rigid body 105, e.g., through the slit 125 formed between theouter edge of the front cover 115 and the outer edge of the side cover120 of the front rigid body 105 shown in FIG. 1. As shown in FIG. 2B,the heat pipe 215 at least partially surrounds a periphery of the hybridfan 205. In this way, the heat can be transferred away from the one ormore electronic components of the PCB 210 including the CPU 230 moreefficiently. More details about air flows for discharging heat out ofthe HMD 100 are disclosed in conjunction with FIG. 3.

FIG. 3 is a cross-sectional view 300 of the front rigid body 105 of theHMD 100 in FIG. 1 taken along line A-A′ of FIG. 2B. In FIG. 3, flow ofair within the HMD 100 is illustrated. As discussed above, the hybridfan 205 pulls air 305 from a rear side of the front rigid body 105. Thehybrid fan 205 pulls the air 305 from, e.g., an area 310 that includes acavity between a face of a user wearing the HMD 100 and the front rigidbody 105 to cool down temperature in the cavity. As shown in FIG. 3, theair 305 is sucked from the area 310 through the hybrid fan 205 and thenexhausted as air 315 radially around a periphery of the hybrid fan 205.After that, the air 315 is pushed along at least a portion of an innersurface of the front cover 115 out of the front rigid body 105 throughthe slits 125. In some embodiments, the exhaust of the air 315 isrestricted over a portion of a whole circle (360°) around the peripheryof the hybrid fan 205. The restricted exhaust of the air 315 may serveto direct flow of the air 315 preferentially over thermally sensitiveparts of the HMD 100, such as for cooling of the one or more electroniccomponents of the PCB 210 including the CPU 230.

As discussed in conjunction with FIGS. 2A-2B, the heat pipe 215 (notvisible in the cross-sectional view 300 in FIG. 3) partially surroundinga periphery of the hybrid fan 205 transfers heat and air away from theone or more electronic components of the PCB 210 including the CPU 230.The heat pipe 215 is connected to the metal frame 220 (not visible inthe cross-sectional view 300 in FIG. 3) that acts as a sink for the heattransferred away from the one or more components of the PCB 210. Themetal frame 220 spreads the heat, which helps discharging the heat outof the front rigid body 105, e.g., through the slits 125. Thus, the air315 shown in FIG. 3 may include the air 305 sucked from the area 310(i.e., from the rear side of the front rigid body 105) and the heattransferred away from the one or more electronic components of the PCB210 by the heat pipe 215.

As discussed above in conjunction with FIG. 1 and further shown in FIG.3, the front cover 115 is attached to the side cover 120 with the slit125 between each outer edge of the front cover 115 and each outer edgeof the side cover 120 to discharge the air 315 from the hybrid fan 205and out of the front rigid body 105 and the HMD 100. As shown in FIG. 3,the air 315 flows at least partially along the inner surface of thefront cover 115 and then out of the front rigid body 105 through theslits 125 formed between the front cover 115 and the side cover 120. Bypulling the air 315 through the slits 125 out of the front rigid body105, heat generated inside the HMD 100 by the one or more components ofthe PCB 210 and/or by the user's face is discharged out of the HMD 100.

FIG. 4 is a rear view 400 of the front rigid body 105 of the HMD 100 inFIG. 1, showing a view of the hybrid fan 205 from a facial interface 405of the HMD 100, in accordance with an embodiment. A user wearing the HMD100 places a face on the facial interface 405. While wearing the HMD100, the user generates heat on its face, i.e., in a cavity between theface of the user and a front side of the front rigid body 105.

As discussed above, the hybrid fan 205 pulls warm and moist air from arear side of the front rigid body 105 to the front side of the frontrigid body 105, i.e., from the facial interface 405 to the front side ofthe front rigid body 105. Therefore, the hybrid fan 205 transfers thewarm air and heat away from the face of the user and/or from the facialcavity through the hybrid fan 205. After that, the hybrid fan 205exhausts the air at the sides of the hybrid fan 205 and along at least aportion of the inner surface of the front cover 115 (not shown in FIG.4) and through the slits 125 (not shown in FIG. 4) formed between thefront cover 115 and the side cover 120 out of the front rigid body 105.Thus, in addition to cooling the one or more electronic components ofthe PCB 210 including the CPU 230, the hybrid fan 205 helps keep theuser's face more comfortable and mitigates fogging of lenses 410. Heatfrom the one or more components of the PCB 210 including the CPU 230 istransferred by the heat pipe 215 (not shown in FIG. 4) along at least aportion of the inner surface of the front cover 115 and through theslits 125 out of the front rigid body 105, as discussed in more detailin conjunction with FIG. 3.

The language used in the specification has been principally selected forreadability and instructional purposes, and it may not have beenselected to delineate or circumscribe the inventive subject matter. Itis therefore intended that the scope of the disclosure be limited not bythis detailed description, but rather by any claims that issue on anapplication based hereon. Accordingly, the disclosure of the embodimentsis intended to be illustrative, but not limiting, of the scope of thedisclosure, which is set forth in the following claims.

What is claimed is:
 1. A head-mounted display (HMD) comprising: a fanhaving a center axis extending from a rear side of the HMD to a frontside of the HMD, the fan configured to pull air from a rear side of theHMD; at least one processor separated from the fan, the at least oneprocessor generating heat during operation of the HMD; a heat pipe atleast partially surrounding a periphery of the fan and transferring theheat away from the at least one processor; and a metal frame onto whicha circuit board comprising the at least one processor is directlymounted, wherein the metal frame receives the heat from the heat pipeand dissipates the heat.
 2. The HMD of claim 1, further comprising: aside cover enclosing the fan, the at least one processor and the heatpipe; and a front cover attached to the side cover with a slit betweenan outer edge of the front cover and an outer edge of the side cover todischarge the heat out of the HMD.
 3. The HMD of claim 2, wherein themetal frame is enclosed within the side cover.
 4. The HMD of claim 2,wherein the metal frame has edges shaped with contours that match aninternal contour of the side cover to support the side cover.
 5. The HMDof claim 1, wherein the air flows at least partially along an innersurface of a front cover of the HMD and out of the HMD through slitsformed between a front cover and a side cover of the HMD.
 6. The HMD ofclaim 1, wherein the fan is further configured to pull the air from acavity between a face of a user and the HMD to cool down a temperaturein the cavity.
 7. The HMD of claim 1, wherein an end of the heat pipe iscoupled to the at least one processor via a thermal interface material.8. The HMD of claim 1, wherein the heat pipe is horseshoe shaped with afirst member coupled to the at least one processor, a second memberextending parallel to the first member and a third member connecting thefirst member and the second member.
 9. The HMD of claim 1, wherein theheat pipe comprises a first member coupled to the at least one processorand a second member extending parallel to the first member.
 10. The HMDof claim 1, wherein the heat pipe transfers the heat away from the atleast one processor into the metal frame that acts as a heat sink. 11.The HMD of claim 1, wherein the fan is a hybrid fan that exhausts theair at sides of the fan after pulling the air from the rear side of theHMD.
 12. The HMD of claim 1, wherein the fan is further configured topull air from front slots located on the fan and exhausts the air atsides of the fan for cooling the at least one processor.
 13. Ahead-mounted display (HMD) comprising: a fan having a center axisextending from a rear side of the HMD to a front side of the HMD, thefan configured to pull air from a rear side of the HMD; at least oneprocessor separated from the fan, the at least one processor generatingheat during operation of the HMD; and a metal frame onto which a circuitboard comprising the at least one processor is directly mounted, whereinthe metal frame receives the heat and dissipates the heat.
 14. The HMDof claim 13, further comprising: a side cover enclosing the fan, the atleast one processor and the heat pipe; and a front cover attached to theside cover with a slit between an outer edge of the front cover and anouter edge of the side cover to discharge the heat out of the HMD. 15.The HMD of claim 14, wherein the metal frame is enclosed within the sidecover and has edges shaped with contours that match an internal contourof the side cover to support the side cover.
 16. The HMD of claim 13,wherein the fan is further configured to pull the air from a cavitybetween a face of a user and the HMD to cool down a temperature in thecavity.
 17. The HMD of claim 13, further comprising a heat pipe at leastpartially surrounding a periphery of the fan, the heat pipe configuredto transfer the heat away from the at least one processor.
 18. The HMDof claim 13, further comprising a heat pipe having an end coupled to theat least one processor, the heat pipe configured to transfer the heataway from the at least one processor.
 19. The HMD of claim 13, furthercomprising a heat pipe that includes a first member coupled to the atleast one processor and a second member extending parallel to the firstmember, the heat pipe configured to transfer the heat away from the atleast one processor.
 20. The HMD of claim 13, wherein the fan is ahybrid fan that exhausts the air at sides of the fan after pulling theair from the rear side of the HMD.